Happy, a young resident of Dodeka Tree, is always bullied and called weak. He seeks out his idol Anpanman and asks him to teach him and help him become strong. When Anpanman spends his days helping people in need rather than fighting bad guys, Happy loses his faith in him. This offers Baikinman an opportunity to step in and wreak havoc with Dr. Hiyari's new creation, a gluttonous maggot Gringa.